50 SAVAGE SQEVIVALS 



not only in form and structure, but also in their 

 natures and ways of acting. Animals have not 

 only the organs and parts in their bodies which 

 they need in order to enable them to live, but they 

 have also the instincts to drive them to do the 

 things they need to do in order to enable them to 

 live successfully. Every being has a certain set 

 of urges in its nature pushing it to do things, and 

 these urges are generally useful. But when a 

 species in the struggle for life is driven out of one 

 set of surroundings into another set different from 

 the first, it is likely to have some instincts and 

 ways of acting that are not needed in the new 

 environment. These useless instincts are called 

 Vestigial Instincts. 



Vestigial instincts are merely instincts which 

 have been thrown out of employment by changes 

 in conditions imposed by the struggle for life. Men 

 and other animals have many ways of acting that 

 are useless, just as they have many organs that 

 are useless. These ways of acting survive wholly 

 thru momentum acquired in times gone by. Like 

 the vermiform appendix and the eyes of cave 

 fishes, they have gone out of use, but have not yet 

 gone out of existence. 



Domesticated animals have been subjected to 

 very great changes in surroundings, and they 

 have, for this reason, an unusually large number of 

 instincts that are useless. These instincts have 

 been imported. They can be understood only by 

 reference to the wild conditions in the midst of 



